Fire control mechanism



Sept. 27, 1949. A. F. @Amos FIRE CONTROL MECHANISM 4 Filed Sept. 3, 1946 3 Shee'ts-Sheet l .m E mm 3u E .E Z

Sept. 27, 1949u A. F. GAlDos FIR CONTROL MECHANISM 5 Sheets-Sheet 2 Filed Sept. 3, 1946 Sept. 27, 1949. A. F. GAlDos' 2,482,758

FIRE CONTROL MECHANISM l Filed sept. s, 194e v s sheets-sheet 5 Avlnzn' E Euidn Patented Sept. 27, 1949 FIRE rCONTROL MECHANISM Alamo Gaidosgtltdwood City, Calif., assgnr v .t0 the Anite@ ates of by the Secretary fWar Application septembei s, 19.46, serial No. 94,443

` s .claims (o1. sea- 140) -iGranted 11n-der .act of March 3, 1883, as

amended April 230, 1928; 370 .0. G. 755') The invention described herein may be manufactured and `used by or for the Government ier governmental purposes, without .fthe payment to me of any royalty thereon.`

This invention relates to a iire control mechanism' for firearms, more particularly `to a rire control mechanism having asliding scar to effect semi-automatic or full automatic iire control.

Fire control mechanisms for automatic iirearms are generally highly complicated mechanisms. Such mechanisms contain -a large number of parts which are diicul-t to manufacture and likewise hard to assemble to the firearm. Still another drawback to most 'rire control mechanisms is the difculty of obtaining a `satistactcry trigger pull.

Accordingly, it is an obiect of this invention to provide an improved nre control mechanism having both semi-automatic and full automatic i'ire control. l

Another .object ef 4this invention is to provide a fire control mechanism for a iirearm a sliding 4sear permitting semi-automatic and fuli automatic lire control. r

Still another Iobject of -this invention-is topa vide a fire .control mechanism vhaving both semiautomatic and fullk automatic iire control iorany rearm having a recoiiling'lbreech member.

Another .object of this invention 4'is to provide a fire control mechanism for a firearm wherein automatic re is .obtained from the .open lbolt position and wherein semifautomatic rire is Volotained from the :closed bolt position.

The specific nature` of the invention as well as other objects and advantagesthereof will clearly appear .from a description of 'a preferred embodiment Aas shown in the accompanying drawings in which:

Fig. 1 is a vfragmentary longitudinal sectional view of 4a firearm showing .the rire control mechanism in the semi-automatic .position 4with the bolt closed .prior to releasing the trigger;

Fig. 2 is a view similar to Fig. 1 but shown in the rull automatic position with the `bolt retracted;

Fig. 3 is a detail view in longitudinal section of the lire vcontrol mechanism shown set vfor Vfull automatic lire and after the trigger has been pulled rearwardly;

Fig. V4 is a view similar to Fig. 3 showing the trigger blocked by the safety;

Fig. -5 -is a front endiview of the iire control mechanism with the "housing Ibroken away to show .the arrangement v--of the scar when positioned If-or semi-'automatic rire;

America ,as represented Fig. 6 is an enlarged detail view of the sear sho-wn in longitudinal sect-ion;

Fig. 7 is an enlarged detail perspective view of the pawl; Y

Fig. 8 is an enlarged 'detail side elevational View of the safety;

Fig. 9 is an enlarged detail `view of the safety handle;

Fig. 10 is an enlarged detail perspective view of the trigger; and

Fig. 1i is a bottom plan view of the actuator showing the lugs for full automatic :re and 'semiautomatic lire.

In Fig. 1 there is show-n 4in assembled relation the re control mechanism embodying this invention. Such mechanism is contained within a trigger :guard housing I and comprisesm-ainly a trigger 2, a scar 3 and a paw! 4.

Trigger 2 (Fig. 109 is provided with a conventional curved portion 5 for engagement thereof by the llinger of the operator. A transverse hole 6 is provided .at the top of trigger -2 for pivetally mounting such trigger on a transverse pin in trigger guard housing l. A rearwardly projecting `lug 8 is provided on trigger '2. The -upper surface of suchflug is horizontal-ly disposed as shown at -9 and a flat-leaf type-spring I'I 0 rests thereon Vto bias trigger '2 `in a counterclockwisedirection as shown in Figs. 1 and 2. Leaftsprin-g i0 is secured to trigger guard housing lY by a screw H. A transverse lug i2 is provided on the `forward part of trigger 2 in alignment with hole 6. Substantially onehalf of transverse lug |12 is nolf reduced width thereby providing two forward-ly projecting lugs i3 and 14, the lug i3 Eheir-1g of narrower width than lug 1.4. The forward edges of such lugs are bevelled as shown at l5.

Sear 3 comprises essentially two arms 46 and il' disposed at an acute angle as shown in 2, 3, 4 @d 6. Art-ransverse hole I8 is provided at the juncture .of arms i6 and l1 for mounting scar 3 on a transverse pin +9 provided with an integral head i9. Such `pin is transversely mounted in trigger guard ousing I which is on the upper A-Vforward portion thereof.

On the A'other end of pin i9, a head portion 2B (Fig. i5-) is secured by vasi-iitafple transverse pin 2U and this is provided to facilitate sliding s ear 3 transversely `Vwith respect to housing l, as will y be later described. lThe apex of scar 3 iormedby the juncture kof arms It and ISI is bifurcated as shown-at -2 l'. Such-bifurcation is somewhat deeper than hole i8 andis provided to `permit mounting a torsion spring 22 on pin 19 to bias scar f3 upwardly.

A cylindrical recess 21 is provided inthe bottomV of bifurcation 25 in which isplaced a spring 28 which bears against pawl 4. Pawl 4 is a substantially L-shaped member as shown in'Fig.' '1 and its upright arm is of reduced thickness to permit such to be inserted withinthe bifurcation 25, as shown. A transverse hole 29 provided in pawl 4 permits such pawl to be pivotallyse'cur'ed to arm I1 of sear 3 by transverse pin 30 which is inserted through hole 24 of arm I1 and hole 29 of pawl 4. A cylindrical recess 3| in the horizontal arm of pawl 4 receives the other end of spring 28 contained in the recess 21 of sear 3.

Thus spring 28 is adapted to bias pawl 4 in a counterclockwise direction. The movement of pawl 4, however, is limited by the end 32 of the upright arm of pawl 4 which, as stated, contacts the bottom of bifurcation 25 in sear 3.v The extreme end of the horizontal arm of pawl 4 is arouately formed as shown at 33, for a purpose which will be presently explained.

The arm I6 projects upwardly through trigger guard housing I as shown in Fig. 1, to engage an actuator 34 of a rearm which is generally indicated by the numeral 35, as will be later de scribed. The upward movement of vsear 3 is limited by the forward portion of arm I6 and said forward portion strikes vthe top of trigger guard housing I in such away as to limit the upward movement of sear 3.

It is to be understood that the reY control mechanism herein described may be utilized by any firearms having a recoiling breechmember. .One of such firearms is illustrated in Fig. 1 kand comprises mainly a receiver 33 in which the actuator 34 is slidably contained in any conventional manner. A rearm bolt 31 is likewise slidably mounted in suitable ways (not shown) directly above actuator 34. Connection between bolt 31 and actuator 34 is made by integral lug 38 provided on actuator 34 `adapted to enter a suitable locking cam slot 31' provided on the underside of bolt 31.

A firing pin 4|) is provided in a suitable axial recess 4I in bolt 31. Lug 38 of actuator 34 engages two oppositely disposed shoulders 42 which l are provided on firing pin 4I] formed `by a suitable transverse slot 42'. ,'Suchengagement is provided to cock firing pin 40. Y

Arspring 43 surrounding firing pin 4G biases it forwardly to discharge a cartridge in firearm 35. One end of a driving spring 44 is contained Within an axial recess 45 provided in actuator 34. A driving-spring-guide rod 46, provided to support spring 44, has one end removably secured to a buffer meohanismgindi'cated generally by numeral 41 as shown in Fig. 2 while the other end of spring 44 abuts the forward face of axial recess 45 of actuator 34.

On the bottom surface of actuator 34 there is provided an integral transverse lug 49 having a lsloped forward surface 50 for engagement therewith by surface 26 of sear 3. Lug 49 is positioned near the forward end of actuator 34 and extends approximately halfway acrosssuch actuator as shown in Fig. 11. There is a transverseglug 5I 4 on the extreme rear end of actuator 34 and a sloped surface 52 is provided on the forward face thereof which is engaged by surface 25 for semiautomatic fire as will be later described.

The re control mechanism herein described is readily set for semi-automatic re when sear 3 is moved transversely with respect to housing I by hand portion 2U of pin I9 so that pawl 4 is op posite lug I3 of trigger 2. The firearm bolt 31 is manually retracted in order to cock firing pin 40.

Such cocked position is shown in Fig. 1 and in Y such position arm I6 of sear 3 is raised upwardly as shown so that surface 26 thereof engages sloped surface 52 of transverse lug 5I provided on actuator 34. With the actuator 34 held in A such 'retracted position, lug 38 maintains firing pin 40 retracted in a cocked position and against the bias of spring 43. Trigger 2 is pulled rearwardly to release actuator 34 thereby rotating bolt 31 by the movement of lug 38 through cam slot 31 to permit firing pin 40 to be biased forwardly by spring 43. l

Lug I3 on trigger 2, which is in engagement with arcuate surface 33 of pawl 4, then rotates sear 3 in a counterclockwise direction about pin I9. Such movement then disengages surface 26 of sear 3 from Contact with surface 52 of lug 5I thereby permitting the actuator 34 and firing pin 40 to be biased forwardly to effect discharge of a cartridge. Continued pressure on trigger 2 causes further rotation of the sear 3 so that lug I3 slips off the end of pawl 4, whereupon sear 3 is immediately biased upwardly by torsion spring 22 with the resultV that arm' I6 is immediately raised into the path of lug 5I on the extreme rear end of actuator 34. Thus sear 3 will engage actuator member 34 to cock firing pin 44 before the bolt has fully closed.

Lug 38 of actuator 34 holds the bolt 31 and actuator 34 in locked relationship prior to the release of Sear 3 as shown in Fig. 1. Cam slot 31 of bolt 31 has a cam shoulder which engages lug 38 of actuator 34. When actuator 34 is released from the position as shown in Fig. 1, the bias of the driving spring 44 urges actuator 34 forwardly rotating bolt 31 a partial turn to a locked battery position. Lug 38 of actuator 34 then carries the firing pin 40 forwardly to the firing position.

According to the preferred form of the invention, the sear 3y can not be disengaged from lug 5I until pressure of trigger 2 has been released. Thusa flat spring 'Ill is provided to bias trigger 2 forwardly so that lug I3v will pivot pawl 4 upwardly about pin 30 against the bias of spring 28 whereby lug, I3l can again reston arcuate surface 33 of pawl 4 and trigger 2 will again be in position to effect'release of sear 3 from actuator 34. It is desired ,toy point out that when pressure is applied to trigger' 2, pawl 4can rotate in only one direction. Such is effected by end 32 of pawl 4 contacting the bottom bifurcation 25 thereby permitting only rotation of pawl 4 in a counterclockwise direction as shown in Figs. 1, 2, 3, and 4.

To obtain full automatic fire', sear 3 is moved transversely with respect to housing I by the member 20 to bring pawl 4 opposite lug I4 as shown in Fig. 3. In such position of the sear, only engagement of lug 49 by the scar to obtain automatic re is possible and lug 5I is utilized only for semi-automatic nre-from the closed boltposition. As automaticjring is obtained from the open bolt position; bolt 31 is manually retracted to open position whereupon surface-23 of Sear ,13

amarga 5 engages .sloped surface .t aoiV lug 19 provided' on the underside or actuator l 3 4 so as ttohold actuator 34 `aijidhence bolt 31 Ainthe retracted .posi-- tion.

Thereupon actuator 34 is released to permit it, as well as bolt 131, to go forwardly to discharge a cartridge when trigger 2 is pulled rearwardly. A rearward pull ontrigger 2 rotates sear 3 in a counterclockwise direction as lug I4 rests on top of the arcuate surface 33 of pawl 4, thus end 26 of sear 3 is rotated out of Contact with sloped surface 50 of lug 49 thereby releasing actuator 34 and permitting both actuator and bolt to be biased forwardly by driving spring 44 to eiect discharge of the rearm.

In the full automatic position, lug I4 is at all times maintained on top of arcuate surface 33 of pawl 4, hence when trigger 2 is pulled rearwardly, surface 26 of sear 3y is maintained out of contact with sloped surface E0 of lug 49 on actuator 34. Thus the firearm will continue to fire automatically as long as trigger 2 is held rearwardly or until the cartridges contained in the magazine or belt are exhausted. Release of trigger 2 permits torsion spring 22 to immediately bias sear 3 upwardly into the path of lug le to hold actuator Ed and hence bolt 37 in the retracted or open position.

Trigger 2 is conveniently blocked by a safety 53 to prevent discharge of the firearm. Such safety is transversely mounted in guard housing l and comprises a pin 54 provided with attened ends as shown at 55 in Fig. 8. A handle 5S, shown in Fig. 9, may be mounted on either of such flattened ends. A transverse slot '51 is provided centrally on pin 5A to permit trigger 2 to be pulled rearwardly when such slot is aligned with the rear of such trigger by handle 56. Trigger 2 is blocked when such slot is rotated away from from the trigger. A suitable detent 58 is provided to yieldingly secure safety 53 in either the safe or ready position.

From the foregoing description it is therefore readily apparent that there is hereby provided a simple, easily constructed re control mechanism for a rearm that will provide full automatic re from an open bolt position or semiautomatic nre from a closed bolt. Such mechanism is positive in operation and will provide a somewhat positive sear release.

I claim:

l. The combination in an automatic firearm having a reciprocating breech member movable between a battery position and a recoil position of, an actuator engaging the breech member, a sear pivotally mounted on the rearm having means for selectively moving said sear transversely with respect to the rearm to either of two spaced positions, rst means on said actuator engageable by said sear when in one of said two positions whereby semi-automatic fire is obtained when the breech member is in battery position, and second means on said actuator engageable by said Sear when in the other of said spaced positions whereby full automatic iire is obtained from the recoil position of the breech member.

2. The combination in an automatic rearm having a reciprocating breech member movable between a battery position and a recoil position of a firing pin mounted for limited longitudinal movement within the breech member, said firing pin having a transverse slot thereon, an actuating member engaging said slot, resilient means associated with said actuating member and the breech member adapted to bias the same to battery position, and a scar `pivotally mounted on the firearm having means for selectively positioning said sear transversely with respect tothe rearm to either of two spaced positions, all adapted and arranged whereby when, said sear is engaged in one of said two spacedpositions with said actuating member with the breech member in the-.battery position saidactuatingmember and said firing Vpin are heldretrated. until release or said sear and whereby semi-automatic fire is obtained and whereby when said sear is in the other of said spaced positions, the said actuating member and the breech member are held in the recoil position until release of said sear whereby automatic re is obtained.

3. The combination defined in claim 1 wherein said first means comprises a rst transverse Sear engaging projection provided on the rear portion of said actuator and wherein said second means comprises a second transverse sear engaging projection provided on the forward portion of said actuator, the second-named projection extending only halfway across said actuator so that when said sear is positioned for automatic re said sear engages said second-named projection.

4. A fire control mechanism ior an automatic firearm having a receiver comprising, a trigger pivotally mounted on the receiver, a sear pivotally mounted on the receiver, means for selectively positioning said sear transversely with respect to the firearm in either of two spaced positions, and a pawl pivotally mounted on said sear engageable by said trigger in one of said spaced positions of said sear to eiect release of said Sear to obtain semi-automatic re and whereby automatic fire is obtained when said sear is moved to the other of said spaced positions.

5. A re control mechanism for an automatic firearm having a receiver comprising a trigger pivotally mounted on the receiver, said trigger having a first and a second sloped transverse lug thereon, said second lug being substantially longer than said first lug, a sear pivotally mounted on the receiver, means for selectively positioning said sear transversely with respect to the firearm in either of two spaced positions, a pawl pivotally mounted on said sear, said pawl normally engaging the underside of either of said first or second lugs depending on the spaced position of said sear, resilient means urging the pivoted end of said pawl into contact with said sear, said sear being arranged for semi-automatic re when moved to one of said spaced positions whereby said pawl lies underneath said rst lug and whereby automatic re is obtained when said sear is moved to the other of said spaced position to position said pawl underneath said second lug.

6. A re control mechanism for an automatic firearm having a receiver comprising a trigger pivotally mounted on the receiver, said trigger having a rst and a second sloped transverse lug thereon, said second lug being substantially longer than said rst lug, a sear pivotally mounted on the receiver, means for selectively positioning said sear transversely with respect to the rearm in either of two spaced positions, a pawl pivotally mounted on said Sear, said pawl normally engaging the underside of either of said first or second lugs depending on the spaced position of said sear, resilient means urging the pivoted end of said pawl into contact with said sear, said pawl being engageable with the underside of said rst lug when said sear is moved to one of said two spaced positions whereby release of said trigger rotates said pawl to effect release of said sear, said pawl underside of said second lug whereupon release of said trigger rotates said pawl to effect release of said sear, said second lug being adapted to maintain engagement of said pawl in the pulled posi- 5- tion of said trigger.

ALONZO F. GAIDOS.

No references cited. 

